Mortisiitg-chisel



GEO. P. KETCHAM, OF BEDFORD, INDIANA.

IVIORTISING-CHISEL Specification of Letters Patent No. 17,285, dated May 12, 1857.

To all whom t may concern."

Be it known that I, GEORGE P. KETCHAM, of Bedford, Lawrence county, Indiana, have invented a new and useful Improvement on Mortising-Chisels; and I hereby do declare that the following is a full, clear, and exact description of the same, reference being had to the annexed drawings, making part of this specification.

Figure l is'a perspective view of one half of my improved mortising` chisel, (eXclusive of the divider` hereinafter mentioned,) the two halves of the chisel being precisely similar in construction. Fig. 2, is a vertical section of the chisel and divider, laterally bisected: Fig. 3 is a vertical section of the chisel and divider transversely bisected: Fig. 4f is an end view of the chisel.

Like letters of reference indicate correspending parts in the several figures.

This invention relates to a new and useful improvement in mortising chisels by which the mortise is cut and cleared of chips or blocks at one and the same stroke of the chisel.

The nature of my invention consists in placing in a hollow, rectangular, mortising chisel a divider as represented in Figs.

2 and 3, by D, and cutting shoulders on the sides of the chisel parallel with the divider as shown by P, in Figs. l and 3; the surface of the shoudder being at the upper edge of the bevel and in the same plane with the edge E, of the divider (Fig. 3.) The chisel being driven into the wood to be mortised, the chip or block thus formed is split into two pieces by the divider, which are forced -up between the divider and the parallel sides. The chips being retained in the chisel by the shoulders, P, Figs. 1 and-3, and torn loose from the wood when the chisel is withdrawn. The chisel being hollow throughout, the chips or blocks will be discharged at the top. y i

To enable others to make and use my invention, I will proceed tol describe its construction and operation.

Construct the two halves of the chisel as shown in Fig. l, making it hollow throughout. Make the flanges (F) (F) sufficiently strong so that when screwed together, they will keep the parts of the chisel closely together. Let the bevel angle (a c) be as small as, possible consistent with a proper strength of the chisel. The shoulders (P) (P) should be madeV deep enough to re tain their hold upon the chips or blocks. The bevel angle (f g L) should be as large or larger than in ordinary mortising chisels. The notches (T) (T) Fig. l intended for the reception of the tenons of the divider (D), should be of sufficient length and depth to hold the divider perfectly fast. The divider D is placed in the chisel parallel with and half way between the sides con-V taining the shoulders, and secured by the tenons (T) (T) Fig. 2. The side edges of the divider mustfitclosely to the `adjoining sides of the chisel so that the entire mortised chips may be split. The lower edge of the divider is beveled from each side, and made on a line with the shoulders. The upper edge of the divider may be any convenient distance above the tenons. The divider should be thick eno-ugh to press the blocks, after splitting, closely against the sides of the chisel so as to give the shoulders a full bite. Place the divider in the notches and make the two parts of the chisel fast together by screens through the flanges as shown fully in Fig. 4L; attach the chisel to a lever in the ordinary mode employed for driving mortised chisels, and it is ready for work. The operation being sufficiently above set forth need not be now repeated.

This improvement is simple, easy of construction and difficult to get out of order. In the manufacture of window sash, Venetian blinds, and the like, it will be found to effect a great saving of labor.

Having thus described my invention what I claim as new and wish to secure by Letters Patent is- The employment of the divider D, and the shoulders (P) (P) in combination, as above substantially set forth.

GEO. P. KETGHAM.

Attest: ,f V

A. B. CARLTON, HosEA MURRAY. 

